INVESTIGATIVE DOSSIER · RESEARCHED 03 OCT 2026
BITCOIN PUZZLE #42 · 42-BIT · SOLVED

Bitcoin Puzzle #42

Solved and swept on 30 Jan 2015. The private key for this 42-bit puzzle was found inside [2^41, 2^42) and the balance was moved out.

Why puzzle #42 still matters

A solved puzzle is a benchmark. Running a cracker against it should recover the real private key, which is how you tell genuine code from a toy. Puzzle #42 needs about 2^40 key tests on average.

Re-solve #42 in your browser All 256 puzzle addresses